A chimney breast is no different in technique from any other wall except you just need to consider where the best starting point may be, which is often dictated by the size of pattern on your chosen wallpaper. For large-patterned wallpapers it is important to make sure the most prominent part of the design or motif is centralized on the chimney breast to provide the most balanced effect. If you are wallpapering the whole room, then you need to consider the best starting point in the room as a whole.
Once you have measured the central point on the chimney breast (denoted by the red dotted line), you can then centre the first length.
First length positioned equidistantly over the central vertical line.
Paper to the right of the first length around the external corner and into the internal corner.
Paper to the left of the first length around the external corner and into the internal corner.
Continue all the way around the room, joining in the internal corner to the left of the chimney breast (if papering the whole room).
It can often make more sense to hang your first two lengths either side of the vertical guideline.
Hang the first length to the left of the guideline.
Hang the second length to the right of the guideline (of course, actually butt-joining with the first length).
Continue hanging around the external corners to the left and right of the first two hangs into the internal corners to either side of the chimney breast.
Continue all the way around the room joining at the internal corner to the left of the chimney breast (if papering the whole room).
Wallpapering a chimney breast options
Which option you choose will depend on the exact design of your wallpaper, and possibly how wide the chimney breast is in relation to your wallpaper width.
In Option 1, the lengths you need to hang either side of length 2 and 3 only have a small amount of wall space before bending around the external corners. The smaller the distance to the corner, the trickier it is to hang the length, so unless your design of paper makes this situation absolutely necessary, then you may prefer Option 2.
With Option 2, you have a wider expanse of wallpaper before the external corner, making it an easier length to hang than in Option 1.
Whichever option you choose, you must always be governed by centralizing the pattern in the most eye-pleasing way, and to complicate matters, some wallpaper manufacturers will slightly offset a central motif on the wallpaper, so you need to adjust your vertical starting line accordingly.
Also note that it is vital to centralize a design horizontally. In both options, the top and bottom points align with the ceiling junction, mantel piece and floor. In reality you'll be lucky to get as good a position as this, so you need to shift paper up and down to find the best point at which each junction cuts through the paper.
Therefore before you get any paste out, always have a dry length to pin up or hold in position, whilst you decide on the best place to position the first length of wallpaper.
There are indeed a few points to consider here, but don't panic, as when you actually get round to wallpapering the chimney breast, it's not really any different from papering any other wall.